Electromagnetic relays



Dec. 23, 1969 P. v. LHTTLE ELECTROMAGNETIC RELAYS I Filed Dec. 28, 1967Q \I/NV NTOR ATTQRNEYS United States Patent 3,486,142 ELECTROMAGNETICRELAYS Philip Vernon Little, Burnley, England, assignor to Joseph Lucas(Industries) Limited, Birmingham, England Filed Dec. 28, 1967, Ser. No.694,231 Claims priority, application Great Britain, Jan. 16, 1967,2,186/67 Int. Cl. H01h 9/00 US. Cl. 335-203 2 Claims ABSTRACT OF THEDISCLOSURE An electromagnetic relay includes a casing, an electromagnethoused within the casing, and an armature which is urged away from theelectromagnet by a leaf spring, and which is movable towards the electromagnet in response to energisation of the magnet. The armature carries amovable contact which is engageable with a fixed contact in response toenergisation of the electromagnet. The leaf spring and the armature areinterconnected by a deformable link, the length of which is adjustableto determine the operating voltage of the relay.

This invention relates to electromagnetic relays of the kind including acasing, an electromagnet housed within the casing, an armature urgedaway from the electromagnet and movable towards the electromagnet inresponse to energisation of the electromagnet, a movable contact carriedby the armature, and a fixed contact engageable by the movable contact.

According to the invention in a relay of the kind specified, thearmature is urged away from the electromagnet by a leaf spring, the leafspring and the armature being interconnected by a deformable link whichis adjusted to determine the operating voltage of the relay.

One example of the invention is illustrated in the accompanying drawing,which is a sectional view of an electromagnetic relay.

Refering to the drawing, the relay includes a moulded synthetic resincasing 11 of open box like construction, having a base 12. Theelectromagnet 13a of the relay is housed in the casing 11 and the coil13 thereof is wound on a moulded former 14. Secured to the former 14 aretwo pairs of conductive blade terminals 15, 16 (one of each of which isseen in the drawing), the terminals 16 each including a contact adjacentthe coil 13 while the terminals 15 are connected to the ends of the coil13 respectively.

The core 17 of the electromagnet 13a extends axially through the coil 13and is parallel to the base 12. Secured to one end of the core 17 is onelimb of an L-shaped member 18, the other limb of which extends parallelwith the core 17 and carries at its free end the armature -19 of therelay. The armature 19 extends at right angles to the core 17 andcarries at its end remote from the member 18 a bifurcated conductivemember 21 having integral therewith a pair of contacts 22 (only one ofwhich is visible in the drawing). Also secured to the core 17 andextending for part of its length in contact with said one limb of themember 1 8 is a leaf spring 23 and extending between the free end of thespring 23 and the end of the armature remote from the member 21 is aductile wire link 24. The link 24 is formed at its ends 'ice with hookportions which extend through holes in the spring 23 and armature 19respectively.

During assembly of the relay the terminals 15, 16 are engaged with slotsin the base 12, the terminals 15, 1'6 projecting from the base forconnection to respective leads.

Each of the terminals, 15, 16 includes a resilient tab 25 which as theterminal is engaged with its respective slot, is flexed to allow theterminal to pass through the slot. The tags 25 are so arranged that whenthe former 14 engages the inner surface of the base 12, the tags 25 canflex outwardly to engage the outer surface of the base 12 and therebyprevent withdrawal of the assembly from the casing.

The operation of the relay is as follows:

When the coil 13 is energised, the armature 19 is drawn against theaction of the spring 23 towards the core 17 and in so doing brings thecontacts 22 into engagement with the contacts 20 so electricallyinterconnecting the terminals 16 through the member 21 and completing anelectrical circuit through the terminals 16. When the coil isde-energised, the armature 19 is returned by the spring 23 so breakingthe circuit through the terminals 16.

When the coil 13 is de-energised, the member 21 engages a rib 28 formedon the wall of the casing 11. However, in a modification, a second pairof contacts are provided adjacent the wall of the casing and in thedeenergised condition of the relay, the member 21 completes a secondelectrical circuit through the second pair of contacts.

In order to set the pull-in and dropout voltages of the relay, it ismerely necessary to kink the link 24, whilst the member 21 is engagedwith the rib 28 or with the second pair of contacts thereby shorteningthe link and adjusting the tension exerted by the spring 23.

After assembly of the relay the open end of the casing 11 is closed by aresilient plate 26, which is snapped into an internal circumferentialgroove 27 in the casing 11.

It will be appreciated that an alternative method of setting the pull-inand drop-out voltages of the relay would be to form the link 24 with akink prior to assembly of the relay, the link then being lengthened orshortened by deforming the kinked portion of the link as required.

Having thus described my invention what I claim as new and desire tosecure by letters Patent is:

1. An electromagnetic relay comprising in combination a. casing, anelectromagnet housed within the casing, an armature urged away from theelectromagnet and movable towards the electromagnet response toenergisation of the electromagnet, a movable contact carried by thearmature, a fixed contact engageable by the movable contact, wherein thearmature is urged away from the electromagnet by a leaf spring, the leafspring and the armature being interconnected by a deformable link, saiddeformable link forming the sole means for adjusting the gap between thefixed and movable contacts to determine the operating voltage of therelay.

2. A relay as claimed in claim 1 wherein the armature and the fixedcontact are carried by a former on which the coil of the electromagnetis wound, the former having secured thereto a plurality of terminalmembers which in use extend through slots in the casing, and the 3terminal members having resilient parts which are flexed to allow theterminals to pass through said slots, the parts then flexing to aposition wherein they engage the easing to prevent withdrawal of saidformer from the easing.

References Cited UNITED STATES PATENTS 4 Rinke '..-.J 335-487 Heyhal.

Valleau 335297 Wright.

Zerwic 335-297 BERNARD A. GILHEANY, Primary Examiner H. BROOME,Assistant Examiner

